Shoe with viscoelastic interior liner

ABSTRACT

A shoe whose upper has an interior liner with a layer contiguous to the foot, provided with a structure having of a viscoelastic substance assembled to a flexible and elastic film. The substance is characterized in that the viscoelastic substance is provided with a high elastic deformation capacity with a low elastic modulus, and in that it is obtained in a thickness from 1 to 5 millimeters. The layer thus structured tends to flatten naturally on the foot and behaves in the manner of a “double skin” that filters the vibrations and the impacts, and which absorbs the micro displacements while preserving the transmission of the tactile sensations.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to shoes in general, whether they have a flexible or rigid upper, and relates to an interior liner of their upper adapted, among other things, to contribute to the comfort of the foot and to ensure the contact with the latter to hold it.

[0003] 2. Description of Background and Relevant Information

[0004] Conventionally, and depending on the type of shoe, the interior liner is assembled either on an inserted padding element or comfort cushion, or directly on the upper. More specifically, in the case of shoes having a relatively high upper, such as ski or hiking boots, the liner is assembled on the inside of a padding element, such as a removable or fixed sock that is inserted between the upper and the foot. Conversely, in the case of sports shoes with a flexible upper, such as tennis shoes, basketball shoes, running shoes, etc., the interior liner is assembled directly on the upper.

[0005] Furthermore, to respect the morphology of the foot as much as possible for the comfort thereof, the interior liner of these various types of shoes almost generally has one or several relatively flexible and/or elastic pieces of fabric or skin on the side contiguous to the foot. Conventionally, these pieces of fabric are composites resulting from the coating or adhesion of a very low density foam on the wrong side of a textile. They are thus capable of conforming to the upper and/or the padding element on which they are assembled, and also capable of deforming subsequently on the foot when the shoe is closed on the latter. The pieces of fabric further procure softness to the touch and a pleasant sensation when putting on the shoe. However, they prove inefficient in dispersing or attenuating any overpressure or hard spot between the upper and the foot, because of their low density and the fact that they compress very easily.

[0006] By way of example, U.S. Pat. Nos. 3,977,098 and 5,765,296 can be cited, which describe a shoe having a rigid upper and a shoe having a flexible upper, respectively, provided with an interior liner having at least one flexible piece of fabric on the side contiguous to the foot, as disclosed previously.

[0007] As is clearly apparent from this prior art, the contact of the interior liner with the foot occurs more or less closely, depending upon whether the boot upper itself is flexible and deformable, and/or whether the padding element inserted between the upper and the foot can conform to the foot. By way of example, U.S. Pat. No. 3,977,098 specifically discloses a solution for adjusting/adapting a padding element, such as an inner sock, coated with a fabric layer on the foot. As is taught, lateral wedges, possibly in the form of impervious packings containing a deformable material, are introduced in pockets located on the outer surface of the padding to adjust the width of the fitting volume to the foot, and thus to ensure that the latter is held in the rigid upper of the boot.

[0008] This method of using a lateral wedging adapted to move the padding toward the foot requires that this padding be made out of a material that can compress easily, if adjusting to the foot is what is desired, or made out of a relatively firm material, if holding the foot is what is preferred. Indeed, a given padding cannot be both easily deformable, for enveloping the foot, and firm, for holding it without slack.

[0009] In the present case, this problem is partially resolved due to the fact that the padding, which is made of polyurethane or foam rubber, therefore compressible, is obtained from a rough shape forming a pair of side panels, and to the fact that it is a lateral wedging in the area of the ankle. Because the rough shape of the padding originally has forms that correspond approximately to the forms of the foot, it is not necessary to firmly tighten the padding on the foot to hold it, because the most projecting portions thereof are housed in the rough shape; moreover, to essentially resolve a problem of lateral wedging, the latter does not require the padding to be closely adjusted, for an approximate coming together of the side panels of its rough shape on the foot suffices to ensure its adjusting to the width of the foot. This wedging and/or adjusting method therefore proves satisfactory, but within strict limits, because the padding does not make it possible to ensure an enveloping/adjusting that accurately assumes the shape of the foot; however, the lack of close contact with the foot considerably blurs the tactile perceptions thereof and therefore disturbs the movements of the boot's wearer, especially when this involves boots secured to equipment or accessories, such as skis, roller skates or ice skates, studs, etc., which are necessary to practice a sport.

[0010] Furthermore, the thinness of the pieces of fabric that cover the padding as well as their texture have no ability to absorb any projecting portion of the foot, and no ability to disperse the pressures which the padding can apply locally on the protruding portions of the foot. Moreover, during use of the boot, and depending on the loads to which the foot is subject, the displacements of the latter with respect to the padding, despite their low amplitude, are not accompanied by these pieces of fabric. As a result, frictions are generated which often constitute a source of blisters, irritations and burning sensations.

[0011] In the example of the shoe described in U.S. Pat. No. 5,765,296, the problem of holding the foot and of adjusting the interior liner on the foot arises in a different manner, because this shoe has a flexible upper provided with foam paddings. Indeed, in a shoe of this type, it is the combination of the flexibility of the upper, the compressibility of the paddings, and the tightening force applied on the lacing that conditions the holding of the foot and the enveloping of the form thereof. The pieces of fabric that cover the interior liner on the side contiguous to the foot also participate in enveloping the foot and, to this end, are made of a soft felt-like material to facilitate the insertion of the foot into the boot. However, as in the case of the padding described and taught in U.S. Pat. No. 3,977,098, these pieces of fabric are too thin and have an overly soft and felt-like texture to contribute to holding the foot in the boot, as well as to absorb any projecting portion of the foot. In addition, due to their close linkage with the boot upper, the deformations which the foot imposes on the latter when walking, running, jumping, etc., and their repetition, ultimately cause these pieces of fabric to delaminate and/or separate. This deterioration that results from pressuring the pieces of fabric against the foot, and from their inability to accompany the latter along these micro displacements, in relation to the upper, further promotes frictions which constitute a source of irritation, burnings, blisters, etc.

SUMMARY OF THE INVENTION

[0012] An object of the present invention is to overcome the disadvantages of the known interior liners and, in particular, it is an object to provide an interior liner which, due to a layer contiguous to the foot, is capable of conforming to the small protuberances and/or projections extending to the surface of the latter, and of accompanying the foot along its micro displacements in relation to the boot upper.

[0013] According to the invention, the layer contiguous to the foot has, at least over a predetermined zone, a structure composed of a viscoelastic substance assembled on a flexible and extensible film, such as a fabric, for example. This structure constitutes the equivalent of a double skin due, in particular, to the thinness and the high elastic deformability of the viscoelastic substance combined with a low elastic modulus. These various characteristics impart to the viscoelastic substance, and thus to the structure of the layer contiguous to the foot, a typical behavior of a so-called “delayed” elasticity, and a natural tendency to lay flat on the foot, in the manner of a viscous gel, by conforming to the small protuberances thereof.

[0014] In this way, the micro displacements of the foot with respect to the boot upper are essentially absorbed by the viscoelastic structure of the layer contiguous to the foot. In fact, the layer thus structured constitutes the interface element between the foot and the boot upper which, possibly mounted on padding, filters the vibrations, the impacts, etc., absorbs the low amplitude displacements, and prevents from involving the skin of the foot to a certain extent, while preserving the transmission of the tactile sensations.

[0015] According to one characteristic, the interior liner includes a layer contiguous to the foot constituted, at least over a predetermined zone, of a structure composed of a non-compressible viscoelastic substance having a low elastic modulus and a flexible and elastic film that can be a woven or non-woven material on which the latter is fixed. According to one mode of construction, the viscoelastic substance is contained in an envelop obtained by means of a flexible and elastic film.

[0016] The viscoelastic substance is, for example, a polymer gel having a density comprised between about 1 and 2 g/cm³, and whose behavior is characterized by a “delayed” elasticity and by an elongation at break capacity greater than 400%, preferably on the order of 700-900%. According to another characteristic, the viscoelastic substance has an Asker C hardness, or a resistance to deformation and penetration, from 15 to 45, preferably from 25 to 30. This hardness is measured with Asker durometers adapted to substances classified as soft rubbers and plastics, including flexible cellular materials and elastomers, according to the SRIS 0101 standard (Society of Rubber Ind. Japanese Standard). Due to these characteristics, the viscoelastic substance can deform under the effect of a stress in the manner of a viscous fluid, because its elongation capacity is substantial, and can recover its initial form as a spring, but after a certain period of time after the stress has ceased, for its modulus elasticity is low.

[0017] In fact, this gel-like substance behaves like a viscous product for slow stresses, and an elastic product for rapid stresses.

[0018] According to a preferred embodiment, the viscoelastic substance is obtained in the form of a thin sheet with a thickness close to 1 millimeter, and on the order of 5 millimeters maximum.

[0019] Its bonding with the flexible film is obtained by adhesive, stitching, welding, etc.

[0020] These various characteristics of viscoelasticity, thickness, and bonding on the flexible film impart to the structure a flexibility that is comparable to that of the pieces of fabric used traditionally, and a certain homogeneity and stability. In particular, gravity flow of the viscoelastic substance is avoided while allowing its deformation under pressure when the boot upper is tightened on the foot.

[0021] According to an embodiment, the layer contiguous to the foot is provided with a structure composed of a viscoelastic substance bonded to a flexible film on at least one zone of the foot having bone protuberances.

[0022] According to another embodiment, the layer contiguous to the foot includes a plurality of predetermined zones each provided with a structure composed of a viscoelastic substance fixed to a flexible film.

[0023] According to an alternative construction of this embodiment, the structure composed of a viscoelastic substance bonded to a flexible film has a different thickness from one predetermined zone to another predetermined zone. For example, in the zones where the bone protuberances of the foot are very pronounced, it is a structure where the viscoelastic substance is relatively thick, for example 4-5 millimeters, that is implemented. In this way, localization of pressure spots is avoided due to the configuration of this structure on a large contact surface.

BRIEF DESCRIPTION OF DRAWINGS

[0024] The invention will be better understood from the description that follows, with reference to the annexed schematic drawings showing two embodiments, by way of example, and in which:

[0025]FIG. 1 shows a perspective view of a boot of the rigid shell type equipped with a comfort padding having an interior liner according to the invention.

[0026]FIG. 2 shows the boot of FIG. 1, seen in a cross-section along the line II-II, with the user's foot positioned therein.

[0027]FIG. 3 shows a cross-sectional view of a detail of the interior liner of the boot.

[0028]FIG. 4 shows a perspective view of a boot having a flexible upper, also equipped with an interior liner according to the invention.

[0029]FIG. 5 is a transverse cross-sectional view along the line V-V of the boot of FIG. 4.

[0030]FIGS. 6 and 7 show a mode of construction of an interior liner, or lining, before assembly on the upper of a boot, FIG. 6 showing the flat developed liner, and FIG. 7 showing a cross-section along the line VII-VII of the liner of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The boot shown in FIGS. 1 and 2 is a ski boot with a rigid upper 1 provided with a comfort padding 2, constituted by a liner, which is inserted between the user's foot 4 and the upper 1. In a known manner, this padding 2 is made out of a microcellular material having a density of less than 1, more or less compressible, such as polyurethane or foam rubber, and has a rough shape having the fitting volume corresponding approximately to the standard fitting volume of a foot 4 in a given size.

[0032] According to an essential characteristic, the padding 2 is covered by an interior liner, one layer 3 of which, contiguous to the foot 4, is provided with a structure 5 where a thin sheet of a viscoelastic substance 6 having a low elastic modulus is bonded to a flexible and elastic film 7. This viscoelastic substance 6 is constituted, for example, by a polymer gel having a density comprised between 1 and 2, and its behavior is characterized by a “delayed” elasticity and an elongation at break capacity greater than 400%, and preferably comprised between 700 and 900%. Its hardness, measured with an Asker durometer, is comprised between 15 and 45 Asker C, preferably between 25 and 30 Asker C. With respect to measurements, the thin sheet of viscoelastic substance 6 has a thickness of approximately 2 millimeters and can reach 5 millimeters.

[0033] With these arrangements, the structure 5 of the layer 3 maintains a flexibility that is substantially comparable to that of the pieces of fabric used traditionally, i.e., it can cover the padding 2 by accurately following its forms, and accompany its subsequent deformations when the upper 1 is tightened to close the boot on the user's foot 4. Conversely, because of its non-compressibility combined with its high elongation at break capacity and its density that is greater than that of the padding 2, this structure 5 can conform to the small protuberances of the foot which are not taken into account by the rough shape of the fitting volume offered by the padding 2. Furthermore, when the latter is pressed on the foot 4, via the upper 1 during closure of the boot, the viscoelastic substance 6 of the structure 5 deforms in the manner of a viscous fluid, thinning out in the area where pressures are the highest and thickening in the neighboring space subject to lower pressures. As a result from this behavior, there is a close contact between the structure 5 of the layer 3 and the foot 4, and thus an increased holding sensation that enables the boot user to make more precise movements.

[0034] In fact, a relatively dense and non-compressible layer 3-5 is placed in contact with the foot 4, and a less dense and compressible padding element between this layer 3-5 and the upper 1. In this manner, the layer 3, with its structure 5, plays the role of a double skin because it conforms accurately to the foot, and its high elasticity enables it to accompany the micros displacements of the foot with respect to the upper 1 of the boot, and even with respect to the padding 2. Thus, the frictions that can be generated between the flexible film 7 and the foot 4 are avoided.

[0035] In the example shown in FIGS. 4 and 5, the interior liner including a layer 3 provided with a structure 5, as described with reference to FIGS. 1, 2, and 3, adapted to a shoe having a flexible upper 11. In this case, the layer 3 with a structure 5 is mounted directly on the flexible upper 11 whose contour it follows. Preferably, in view of the fact that the flexible upper 11 adjusts very easily to the user's foot when the boot is closed, and for weight considerations, the structure 5 is provided with a viscoelastic substance in the form of a thin sheet whose thickness is on the order of 1 millimeter. In this way, the ease of adjustment of the upper 11 of the boot is preserved without overly weighing down the latter.

[0036] Nothing prevents using a comfort padding 15 on the flexible upper 11, for example, on the upper edge of the opening for inserting the foot, and from covering this padding 15 or not with the structure 5 of the layer 3.

[0037]FIGS. 6 and 7 show a mode of construction of an interior liner, one layer 3 of which, provided with a structure 5, is associated with a support piece 22 that can constitute a comfort padding. This support piece, possibly configured to nest the viscoelastic substance 6, is fixed to the flexible film 7 of the structure 5, for example, by adhesion of hot-melt films. To facilitate the assembly of this interior liner on the upper of a boot, not shown, the zone 23 adapted to be sewn and/or stitched, such as the edge, is not provided with a viscoelastic substance 6.

[0038] Numerous other adaptations of a structure 5 close to the foot can be envisioned without leaving the scope of the invention. Thus, the viscoelastic substance 6 of the structure 5 can be housed, at least partially, in the comfort padding 2 on the side directed toward the foot 4 of the user. Moreover, the layer 3 contiguous to the foot can be provided with a structure 5 composed of a viscoelastic substance bonded to a flexible film 7, or bonded to any other textile having equivalent properties, over only a portion of the foot having bone protuberances.

[0039] Furthermore, the layer 3 contiguous to the foot can include a plurality of predetermined zones each provided with a structure 5 composed of a viscoelastic substance 6 fixed to a flexible film 7 or a textile, and this structure can have a different thickness from one predetermined zone to another predetermined zone. By way of example, the structure 5 could be localized in the zones 12 and 13 corresponding to the malleoli 12′ and 13′ of the foot 4.

[0040] Finally, a layer 3 provided with a structure 5 can of course constitute the interior liner of a tongue of a comfort padding or of a sock, and/or the tongue 14 coming from the boot upper.

[0041] The instant application is based upon French Patent Application No. 00 00301, filed Jan. 7, 2000, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. §119. 

What is claimed is:
 1. A shoe comprising: an upper having an interior liner with a layer contiguous to a user's foot, said liner including, at least over a predetermined zone, with a structure comprising a viscoelastic substance bonded to a flexible and elastic film, said flexible and elastic film being adapted to be in direct contact with the foot, said viscoelastic substance being a non-compressible material and having a low elastic modulus, said viscoelastic substance being in the form of a thin sheet of polymer gel having a density comprised between about 1 and 2 g/cm³, and a behavior characterized by a “delayed” elasticity and an elongation at break capacity greater than 400%.
 2. A shoe according to claim 1 , wherein the viscoelastic substance is characterized by an elongation at break capacity comprised between about 700 and about 900%.
 3. A shoe according to claim 1 , wherein the viscoelastic substance comprises a thickness comprised between about 2 and 5 millimeters.
 4. A shoe according to claim 1 , wherein the viscoelastic substance is contained in an envelope made of a flexible and elastic film.
 5. A shoe according to claim 1 , wherein the interior liner covers a comfort padding that is inserted between the viscoelastic substance and the boot upper.
 6. A shoe according to claim 5 , wherein the viscoelastic substance is partially housed in the comfort padding on a side directed toward the user's foot.
 7. A shoe according to claim 6 , wherein the layer of the interior liner that is contiguous to the foot comprises a plurality of predetermined zones each provided with a structure composed of a viscoelastic substance bonded to a flexible and elastic film.
 8. A shoe according to claim 7 , wherein each of the predetermined zones has a structure which, composed of a viscoelastic substance bonded to a flexible and elastic film, has a different thickness from a predetermined zone to another predetermined zone.
 9. A shoe according to claim 1 , wherein the viscoelastic substance has an Asker C hardness from about 15 to about
 45. 10. A shoe according to claim 1 , wherein the viscoelastic substance has an Asker C hardness from about 25 to about
 30. 